A simpler solution would seem to be to NOT have them overlap. 🙂

If the issue is that you in that case don't have enough range for each, maybe get an external MIDI keyboard? Then you can play each part individually in the full (same) range.

There's not a way to get MODX to do what you're asking. You're going to have to setup the keyboard to work for you with what's available.

Note that you can shift the octave of the bass - or of the piano - or both - so that when you strike a note on the keyboard - a octave shifted sound of the bass (or piano) will play.

Are you using the bottom octave of the keyboard? Are you using the top keys of the keyboard? If not, then you're going to want to "Note Shift" the PARTs to spread them out without having the overlap.

Here's what would help to devise strategies for you:

1) What MODX do you have? MODX6 MODX7 or MODX8?
2) What is the note range of your bass line? (Lowest note to highest note & number of notes/octaves between)
3) What is the note range of your piano line? (Ditto)
4) Are there times where either the highest notes of the bass or lowest notes of the piano will be played without the other instrument at the same time? If so, do these lowest/highest notes (where the overlap is) occur exclusively? Meaning only by themselves without the other instrument. Not a big deal if this isn't true.

Also note that if bass is only low during the intro - and not after that - and the piano is low-to-mid then you can use the octave button [-] to shift the notes down to the lower octave for the intro then octave shift up [+] for the main part of the song where perhaps the bass is higher and piano is playing higher as well. I often used (when I had a -6 keyboard) the octave button to give me a different "split" in the lower octave then press the octave [+] button once or twice to give a different range.

But you may not need to do any of that if we find you can map your bass and piano on the keys you have in front of you.

Thanks everyone for your input -- I really do appreciate it. Please do keep in mind that I am not recording a pattern or song, I am playing everything live.

OK, so I am using a MODX7 which goes from A0 to A6. Therefore, if I'm playing a song in Db which is very common in Gospel music, I tend to run out of keys on the low end. A real bass goes down to E0 (or D0 for a five string bass). So generally, I will camp in the mid-range, and use the lower octave for a punchy chorus, and the high end for embellishments.

I'm not playing bass notes "per se" on the piano part, but Jason's 4th point is valid since the piano is being sounded on it's lower end during the intro and this could be managed with scene changes with Keyboard Control enabled.

BTW, I did in fact add my Arturia KeyLab 61 as the 2nd tier since it has switches for easily changing the MIDI channel. That way I can add my various solo instruments to Parts 6, 7 and 8 for example and easily switch between guitar, sax and organ solos. And since I'm a one man band, I would have to pre-record the changes before attempting to pull that off in a live setting.

I will confess that I do struggle with playing when my hands aren't close together -- for example, if I'm playing on two different tiers or with my hands 2+ octaves apart. Of course, that's just a matter of practice.

So until I get the courage to submit Artificial Intelligence as the hottest feature of some futuristic firmware update via IdeaScale, it's probably best for me to just keep practicing.

I've thought that it would be nice to have a "follow" feature where you can give a range outside the top/bottom of the note range where the instrument will "stretch out" of bounds if the note was no more than some programmable threshold from the last "inside" note. This would allow "following" if you moved close to prior notes inside the note range - but would not play notes outside of the note range for large jumps. Allowing for the other instrument to sound instead.

Science fiction wouldn't be that difficult to accomplish. Wearing some kind of glove that would tell a sensor which hand is covering which note range. Or infrared detectors and one hand that is covered with material that blocks the IR energy. Most of this is going to be fairly expensive. Not too popular if it adds lots of weight and is a "pain" to use.

Not really aware of what your full ranges are for Bass+Piano - so it's difficult to determine what could be done here.

Sometimes I have trip points too where a note will "turn off" some other instrument in an automated way and I reset the tripwire with a scene change. I do this in cases where I can't press the scene button fast enough to change the sound between one and the other. If I'm doing a quick run and "on a dime" - the sound needs to change at the end of it for another quick run (two hands). I'll use motion sequence (ARP triggered) or control ARP to change levels of PART(s).

Floating split points (i.e. they move based on proximity to the last notes played) have been around for a while. It's a feature of Mainstage, described at https://support.apple.com/kb/PH13582?locale=en_US . The earliest implementation I've heard of is that you could do it on an old DX7 if you had Grey Matter's E board installed. Anatek had a little box called Pocket Split that supported it... dig up one of those and you could put it between a controller and a MODX (or possibly make use of it between the MODX MIDI OUT and MIDI IN with Local Off).